Is it considered okay (standards-wise) to mix HTML 4 and HTML 5? [closed]

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Closed 8 years ago.

I'm basically wondering wether or not it's considered okay (standards wise) to mix HTML 4 and HTML 5.

For instance, what if I have an HTML 4 body element with an HTML5 audio tag in it. I know it works and renders properly, but is it okay standards-wise, and will my SEO value be penalized by it?

Edit As a lot of posts pointed out, HTML 5 has a body element too. Apparently, only a few elements are deprecated and marked as obsolete every time a new HTML standard arrives. Please don't downvote my question now, since I think there are others misunderstanding this too. That way, I don't have to delete it.

Answer 1

The elements you specified are both HTML 5, hence you aren't mixing anything.

(If you give a better example of perhaps what issue you're facing, or which elements you are thinking of, perhaps we can elaborate.)

Using HTML 4 elements is safe in HTML 5, since new elements are introduced and only a few deprecated ones were dropped.

Answer 2

It is okay, there is nothing wrong in mixing. However you need to provide fallback for html5 elements that aren't supported in older browsers. You might need to include some libraries like Modernizer and shiv to make things seamless.